Continuous-process rotary plaster calciner, drier, and roaster.



y W. A. BISHOP. CONTINUOUS PROCESS ROTARY PLASTBR CALOINER, DRIER, AND ROASTER.

APPLIOATION FILED FEB.-l5, 1910.

Patented Ma137, 1911.

3 SHEETS-SHEET 1.

1X i/Im comm after/"91 rm; NORRIS PETERS Patented M3117, 1911.

3 srmms-snnw 2.

} W. A. BISHOP. CONTINUOUS PROCESS ROTARY PLASTER GALUINER, DRIER, AND ROASTER.

APPLICATION FILED PEB.15,1910, 96,3508

rm: NORRIS PETERS co., wnsmuanm, 1x0.

- W. A. BISHOP. CONTINUOUS PROCESS ROTARY PLASTER GALOINBE, DRIER, AND ROASTER.

- APPLICATION FILLED IEB.15, 1910.

350 v Patented Mar. 7,1911.

3 SHEETS-SHEET 3.

UMG (31 m 11mm! rm: NORRIS PETERS 00.. vmsnmarmv, n c.

WILLIAM BISHOP, 0F NEVV'ARK, NEW JERSEY, ASSIGNOR OF ONE-HALF TO CALVIN I TOMKINS, OF NEW YORK, N. Y.

CONTINUOUS-PROCESS ROTARY PLASTER CALCINER, DRIER, AND ROASTER.

Specification of Letters Patent.

Application filed February 15, 1910.

Patented Mar. '7, 1911.

Serial No. 544,084.

To all whom it may concern:

Be it known that I, WILLIAM AnnLL BISHOP, a citizen of the United States of America, and a resident of Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Continuous-Process Rotary Plaster Calciners, Drier-s, and Roasters, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof, and in which Figure 1 is a side elevation of my improved apparatus; Fig. 2 is a longitudinal section through the same; Fig. 3 is an end elevation of my improved apparatus; and Fig. 4 is a transverse section through the apparatus approximately on the line 44 of Fig. 2, parts being broken away for additional illustration.

Heretofore, with few exceptions, the calcining of plaster has been carried on in batches, and such apparatus as has been devised for continuous production has been ineflicient and generally unsatisfactory.

It is very important in the calcining of plaster that the temperature of the material under treatment, and therefore the temperature of the furnace, be controlled within a very few degrees, as any considerable variation in the temperature results in an entirely different product from a commercial point of view. It is also important that, at difierent periods in the process, the heat be raised or lowered in the furnace to conform to the varying conditions of the material under treatment, and that the mate rial be kept constantly moving and mixing, and that the finer particles, which add materially to the value of the product, be not lost by escaping with the moisture which leaves the heated material and escapes as vapor to the open air.

To accomplish all this in an economical andcontinuous manner is the object of my invention.

Referring to the drawings, 7 is the heat generating part of a furnace, which for purpose of illustration I have shown as a coal furnace, with the usual openings and closures for the control of the fire. Oil or gas eous fuel could be used if desired.

8 is a rising forward part, 9 a contracted intermediate horizontal part, and 10 a descending rear part of a heating flue which continues in a depressed second horizontal part 11, and a vertical part 12, to a convenient point for entrance to a horizontal cylinder 13, and which carries the products of combustion away from the furnace. This flue is preferably lined with fire brick throughout its length with the exception of that portion comprising parts 8, 9 and 10, the upper side of which is provided for by the underside of the trough 14 of the calcining chamber 15.

16 is a hopper provided with an automatic feed regulator 16, from which through pipe 17 the material to be treated is fed to the calcining chamber 15, and 18 is the trough of a discharging chamber 19 which may be provided with the screw conveyer 20 operated by means of pulley 21, belt 22, pulley 23 and power shaft 24, the conveyer being mounted in bearings 25 and 26 attached to the outside plates 27 of the furnace structure, and the trough being provided with a spout 28 where the finished product is dis charged from the apparatus.

29 is a pulley on a power shaft and connected by belt 30 to fan pulley 31 operating exhaust fan 32, mounted on bracket or standard 33, attached to a top plate 34 of the furnace.

35 is a pulley on a power shaft, connected through belt 36 to pulley 37 mounted on and driving a cross shaft 38 on which is also mounted a worm 39, operating a worm gear wheel 40 encircling and turning the cylinder 13, which cylinder serves on the inside as a fine to pass the products of combustion from the furnace, and on the outer side as the foundation for a screw conveyer and mixer 41.

The cylinder 13 is mounted on the adj ustable roller bearings 42 and 43 and passes through bearing 42 to the uptake or vertical part 12 and through bearing 43 and worm gear wheel 40 into the curved connecting pipe 44, with which it has close but sliding fit, the pipe 44 being stationary, and conveying the products of combustion to the exhaust fan 32, from which they escape through exhaust pipe 46 to a stack or the open air.

The screw conveyer and mixer 41 is comparatively narrow and is spaced from the surface of the cylinder 13 for the principal portion of its length, but widens toward the discharge end of the calcining chamber 15, until it extends practically from the trough 1 1 of the calcining chamber to the surface of the cylinder. By this construction the material is first passed slowly along by the narrow part of the conveyer, and partly returned through the openings between it and the surface of the cylinder 13, the churning action serving to mix the material, and then as the material becomes calcined and resolves into a somewhat fluid condition, the wider and more solid part of the conveyor, retards or backs up the material allowing it to escape only with the turning of the conveyer and the narrow space between it and the trough, whereby a too quick running out of the material is prevented, and the proper period of treatment accorded it.

The cylinder and conveyer is prevented from endwise movement through suitable thrust bearings i7 and &8.

Attached to several of the cross bracing channel bars 19 of the furnace and mounted thereon are the side and end plates 50 and 51 of a dust collecting box 52 provided with a cover plate 53 and stacks or vents 54. At the bottom of the dust collecting box 52 is a collecting trough 55 in which a small screw conveyer 56, mounted in bearings 57 and 58 attached to the end plates 51, is operated by gearing 59 connected to power shaft 60.

Vapor and fine dust, rising from the material being calcined in the chamber 15, separates, the dust finding lodgment on the stationary inclined sheet metal shelves 61 or the movable sheet metal shelves (32, while the vapor passes upward and out of the vents 54. At intervals the accumulation of dust may be shaken down into the hopper 63 of the collecting trough 55, by a suitable shaker attached or applied to the squared ends 64 of the supporting rods 65 of the movable shelves 62, the flexible free edges of said shelves 62 engaging the free edges of the stationary shelves 61 and vibrating them. The fallen dust passed from the end of the conveyer through space 66 becomes again incorporated with the mass being treated.

By the apparatus above described it will be apparent that raw material, entering from the hopper 16 through the pipe 17, is propelled slowly through the calcining chamber 15, losing its moisture and some dust through the heat and agitation, and being well mixed through the churning action of the spaced part of the conveyer 4C1, recovers most of the fine dust which rises with the vapor through the action of the collecting apparatus and conveyor 56, is propelled more slowly and finally retarded by the solid portion of the conveyer 41, and passes without undue speed into the trough 18 of the discharging chamber 19, and is removed by the cross conveyor 20 to a convenient point for handling.

It is evident that, by the peculiar construction of the furnace and calcining chamber, the intense heat of the rising part 8 of the flue is modified by the comparatively cooler condition of the products of combustion passing through the exhaust end of the cylinder 13, and that the less intense heat of the descending part 10 of the flue is offset by the comparatively warmer condition of the products of combustion in the cylinder opposite that part of the flue. These conditions may be controlled and further modified by opening the air inlets 67 closed by slides 68.

Openings 45 closed by slides 69 are provided for access to the calcining chamber 15, for the purposes of observing temperature, or physical conditions of the material being treated or cleaning out the chamber.

Openings 70 closed by slides 71 are provided in the walls of the dust collecting box for access to the shelves 61 and 62.

The brick walls of the furnace incased by the plates 27 prevent undue radiation of heat.

Having thus described my invention the following is what I claim as new therein and desire to secure by Letters Patent:

1. An apparatus of the character described, comprising a furnace having a main heating flue, a calcining chamber having its underside forming the upper side of the main heating flue, a rotatable cylinder located within the calcining chamber and providing an auxiliary heating flue connected with and extending forwardly from the rearward end of the main heating flue, an exhaust flue with which the forward end of the rotatable cylinder is connected, a screw conveyor and mixer secured to the rotatable cylinder, narrow at its forward part and spaced from the rotatable cylinder and widened at its rearward part to the surface of the rotatable cylinder, means for feeding the material to the calcining chamber and means for driving the rotatable cylinder.

2. An apparatus of the character described comprising a'furnace having a main heating flue, a calcining chamber having its underside forming the upper side of the main heating fine, a rotatable cylinder located within the calcining chamber and providing an auxiliary heating flue connected with and extending forwardly from the rearward end of the main heating flue, an exhaust flue with which the forward end of the rotatable cylinder is connected, a screw conveyer and mixer secured to the rotatable cylinder, means for feeding the material to having vents at the top, and a collecting trough at the bottom of the dust collecting box having a screw conveyer discharging dust into the forward end of the calcining chamber.

3. An apparatus of the character described comprising a furnace having a main heating flue, a calcining chamber having its underside forming the upper side of the main heating flue, a rotatable cylinder located within the calcining chamber and pro viding an auxiliary heating flue connected with and extending forwardly from the rearward end of the main heating flue, an exhaust flue with which the forward end of the rotatable cylinder is connected, a screw conveyer and mixer secured to the rotatable cylinder, means for feeding the material to the calcining chamber, means for driving the rotatable cylinder, a dust collecting box mounted over the calcining chamber and having vents at the top, and provided with inclined side shelves and movable shelves between the side shelves, and a collecting trough at the bottom of the dust collecting 25 box having a screw conveyer discharging dust unto the forward end of the calcining chamber.

WILLIAM A. BISHOP. \Witnesses JOSEPH MUNGLE, F. E. TOWNLEY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

